It is necessary to know the payment system and its instruments in advance so that it can function in the best way. Today, every man is in some way tied to payment transactions and is in within that, we can say, circular movements. With the entering of the Republic of Croatia into the European Union major changes are taking place within the payments and systems of payment. By adopting the new Law on Payment Transactions (NN, No. 133/2009), the payment system reform in the Republic of Croatia was completed. The purpose and aim of this reform is to remove the lack of expertise in the execution of financial obligations between payment service providers. Fundamental feature of these reforms is that the dealings of payment transactions have shifted exclusively to the competence of the Croatian National Bank as central banking institution and commercial banks as depositary institutions of payment system participants.